


Sister Knows Best

by Lysical



Series: Prompt Fics [5]
Category: Batman (Comics), DCU (Comics)
Genre: Brother-Sister Relationships, Cass is the best big sister, Family Feels, Gen, Protective Siblings
Language: English
Status: Completed
Published: 2017-03-04
Updated: 2017-03-04
Packaged: 2018-09-28 06:26:42
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,561
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10077389
Author URL: https://archiveofourown.org/users/Lysical/pseuds/Lysical
Summary: Cass was a big sister. She took the role very seriously.--"Jason, I am right.""Nah," Jason said, and poked his tongue out at her.





	

**Author's Note:**

> For anon, who wanted Cass and Jason being protective siblings. Hope you enjoy, anon. 
> 
> This one is actually a direct sequel to [Fly by Night](https://archiveofourown.org/works/9910217). It provides some extra context so I recommend reading that one first. :D

Cass crept along the rooftop. Red Hood sat on the edge, swinging his feet out back and forth over the streets below. She saw the slight twitch of his shoulders and grinned. "Caught me."

He didn't turn around. "It's not like I wear this helmet because I think it looks cool."

"Cheater," Cass replied. She sat down next to him and swung her feet out as well, hooking her left foot around his right. He didn't pause, just continued to swing their feet back and forth. "They were worried."

He shrugged his right shoulder. The other, Cass knew, was still heavily bandaged. He'd made it worse by running around with Damian. Alfred had been very stern about it.

She stared at the side of the helmet. Jason was not any better than her other brothers at outlasting her silences.

Finally, he sighed. "What?"

"You're supposed to rest," Cass replied. "Penny-One said."

"This is resting," Jason said. "I'm just sitting on a rooftop, minding my own business."

"You're grounded," Cass pointed out, because it was both true and funny. "Robin is at the manor. Only fair."

"That was a joke," Jason whined. His voice sounded strange when he wore the hood. Cass preferred when he didn't have it. "I'm nineteen. He can't actually ground me."

"Come back with me," Cass said. "Or he sends Nightwing next."

It was a good threat. Cass could take him back, even if he was very heavy, but Nightwing could bring him back and fuss at him at the same time.

"Name your bribe," Jason offered. "I'm not going back there tonight, I'm in a bad mood. I'll just end up picking a fight with Bruce."

Cass turned her attention back to their feet and thought about it. "We can go to your safe house. You can play me a new game. Better than reading together."

Jason scoffed. "Maybe if you didn't make me skip the cutscenes."

"Doing is better." She made a grabbing motion with her hands. "Interacting."

"You make me play all the games for you," he said. "You don't even _like_ video games."

"I like watching," Cass replied. "It's our thing."

He sighed, but nodded. Cass beamed, stilling their legs and unhooking her ankle.

"You're a good little brother," she told him, standing up and patting the top of the red helmet. "Race you?"

Jason stood up beside her, wincing and rolling his injured shoulder. He would need more pain medication soon, Cass could tell. "Whatever happened to 'you should be resting'?"

"Your legs aren't injured," Cass replied, bouncing up and down on the balls of her feet. "Ready?"

He reached out with one finger and tapped her on the nose. Then he moved sharply. Cass saw it coming but let him push her, falling over onto the roof top. He took off running as she leapt to her feet and followed.

She was a big sister. Sometimes that meant letting little brothers have a head start.

***

"Why is that man attacking us?" Cass asked. "What did we do?"

"I don't know, Cass. Maybe if we hadn't skipped the cutscenes I could tell you." Jason was lying on his back across the couch, head in her lap. It meant his neck was at an awkward angle for playing their game, but he was relaxed and loose after taking his pain medication. Cass would make sure to have him change positions before he started to hurt.

They were both out of costume, Jason in sweatpants and a t-shirt while Cass wore his hoodie and some leggings she kept in his bottom drawer.

She tangled her fingers in his hair and played with it. "Why are we killing that monster?"

"It exists," Jason replied. "If it exists and we can kill it, we should. Why would we be able to if they didn't want us to kill it?"

Cass cocked her head to the side, thoughtful. "Hard choices. Morals. Games have them sometimes."

"Nah," Jason said.

"It exists," Cass insisted. She knew it did. Tim had talked about it once, with many hand gestures.

"Eh."

She leaned down over his face, blocking his view of the screen. She could hear him continue to push the buttons on the controller. "Jason, I am right."

"Nah," Jason said again, and poked his tongue out at her.

Cass scrunched her nose up and made a face back at him. "Big sisters are always right."

"Someone's been lying to you." Jason leaned up, headbutting her gently. Cass sat back and let him see the screen again. Their character was still alive. Jason smirked. "Hah, I win."

Cass sighed. "Little brothers are annoying."

"Ain't that the truth."

They fell back into silence as Jason played their game and Cass watched, twisting strands of his hair around her fingers. There was another cutscene that she made him skip, and then they had an even bigger monster to fight.

"It exists," she insisted.

"Nope."

"I'll prove it." 

Jason shrugged. "Go ahead. I still won't believe you."

Cass frowned. "I'll prove it with science."

"So what? They proved evolution with science and there are people who still don't believe in that." Jason huffed unhappily as the big monster pushed their character off a cliff. The sound effects as the character landed at the bottom were very realistic.

"Jason died," Cass said sadly, as the screen went from tinted red to black and the 'Game Over' screen appeared.

Jason started laughing. He laughed every time. They always named their character Jason, except for the one time they'd named him Damian and made the real one go red in the face and yell at them very loudly.

"It's not funny," Cass told him. "I liked this Jason."

"It's always funny," Jason replied. "Especially when Bruce is in the room."

Cass considered it for a moment.

"It's a little funny," she conceded.

***

It wasn't as fun to watch the game with the new Jason, so Cass got up and went into the kitchen to make them dinner.

"Wait, what are you doing?" Jason called after her.

"Looking after you," Cass replied, and opened the fridge. "I will make the spicy food that Steph hates so she won't steal it."

"No one likes the spicy food you make, Cass." Jason got up from the couch and walked into the kitchen. He stopped to lean against the counter, rubbing his shoulder. "It's hard to taste when all you can feel is your mouth on fire. Spicy food is an art."

"No." Cass shook her head. "It is a war. Me and Damian. I will win. You can taste test."

"I would rather starve," Jason replied. "But knock yourself out. I'm ordering pizza."

"No anchovies," Cass said, just to hear him laugh.

Her cooking was a success, so spicy she wondered for a while if maybe she had finally burned all her taste buds off, but then Jason's pizzas arrived and he handed over the one he got her.

Cass took a bite and discovered her taste buds were still salvageable.

She'd just scared them again.

"I am close to winning the war," Cass said, sitting down next to Jason on the couch and holding out more of his medicine in her palm, even the drowsy one Alfred had told her to give him. Jason looked at it for a long time before sighing and taking them, tipping them into his mouth and swallowing. Cass narrowed her eyes. "Did you really swallow them?"

Jason rolled his eyes but opened his mouth obediently, shifting his tongue around until Cass finally nodded, satisfied.

"I did it one time," Jason muttered, a bit sulky.

Cass patted him on the head. "Consequences," she said, with the wisdom that came from being another person Alfred no longer trusted to take their medication unsupervised.

She and Alfred had different opinions on what 'necessary' meant.

As well as 'serious injury'.

Jason started to get sleepy soon after, killing their second Jason of the night. Cass got to her feet and tugged at his good arm until he abandoned the controller and let her drag him into his bedroom. She pushed him down onto the bed and waited while he fumbled his way under the covers.

"You staying?" He asked, rolling over and burrowing his face under his pillow.

"I'm not tired yet," Cass replied. "Join you later?"

Jason mumbled something, muffled under the pillow. Cass tugged the blankets up and over his shoulders before leaving the room.

Back in the living Cass took a quick look around before going over to the window by the fire escape. She opened it and climbed out.

Batman was waiting there. His shoulders loosened up when she smiled at him.

"How is he?"

"Sleeping," Cass replied. "I'll take care of him."

"I know you will," he said. "I was just checking in."

Cass nodded. "I'll bring him to breakfast tomorrow. Pancakes?"

"I'll tell Alfred." Batman's lips twitched into a small smile. "Goodnight, Cass."

"Goodnight." Cass watched as Batman grappled away, back to his patrol, before climbing back inside Jason's safe house and slipping quietly back into the bedroom.

"What'd he want?" Jason mumbled, as she climbed onto the bed beside him.

"To say goodnight," Cass said. "Pancakes at the manor tomorrow."

"Cass, no," Jason complained.

"Shh." Cass tugged some of his blanket away and snuggled under it. "Big sister knows best."

**Author's Note:**

> Cass's POV is so much fun! :D
> 
> My fandom tumblr is [here](http://lysical.tumblr.com).


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